Update: News from Polestar confirms the car is a street-legal one-off build, but a production model could come.

"Whether there will be more cars built is an open question," Polestar Marketing Director Hans Bååth said. "First of all we want to get feedback on this first prototype."

Further details on the car are still to be revealed.

Rumours of a new performance flagship in Volvo's S60 range have been settled with the release today of a new preview video for the upcoming Gothenburg City Race.

Details for the new car are thin on the ground, and it remains unclear if Volvo will offer the enhanced S60 as a production model or if it will remain a concept for fans to lust after.

Reports have suggested that the new model, developed by Volvo's racing arm Polestar, will enter the line-up above the existing Polestar-enhanced S60 T6.

According to Swedish website Teknikens Varld, Volvo and Polestar are preparing either an even more powerful version of the car's 3.0 litre turbocharged six, or the Yamaha-built V8 that drives the larger XC90 SUV.

In its existing Australian-delivered form - largely a factory-option ECU upgrade - the S60 Polestar package delivers 242kW and offers a 0-100km/h time of 5.8 seconds.

Other tweaks were expected to include fatter guards for a wider track, but today's teaser image shows that the new S60 Polestar will stay close to the current R-Design kit, while riding on lower suspension and a new wheel design.

Watch for the S60 Polestar to be unveiled on June 16 at the Gothenburg City Race.